package com.gaogao.java;

public class StringBuilderTest {
public static void main(String args[]){
    StringBuilder sb=new StringBuilder("123456");
    System.out.println(sb.hashCode());
    System.out.println(sb);
    sb.replace(2,5,"M");//>=2,<=5一段字符串
    sb.setCharAt(1,'m');
    System.out.println(sb.hashCode());
    System.out.println(sb);
}
}
